As is the case with several teams that are perennial contenders across Major League Baseball, often retooling their roster at the expense of their farm system, the Giants' Minor League system currently leaves something to be desired. The Giants rank 26th in terms of MLB.com's "prospect points," which are assigned to clubs based on their representatives on the Top 100 list, with 100 points going to the team with the No. 1 prospect, 99 to the team with No. 2 and so on..

That, however, is not to say that San Francisco's player development operation lacks luster. The organization's two World Series championships in the past three years would not have been possible without homegrown talent like Buster Posey, Matt Cain, Tim Lincecum, Madison Bumgarner, Pablo Sandoval and others.

But Trade Deadline deals in recent seasons have plundered the Giants' system of highly rated prospects in exchange for proven big league talent like Marco Scutaro, Hunter Pence and Carlos Beltran. The most notable of these is the Mets' No. 1 prospect, Zack Wheeler, who debuted last month and has already added salt to the Giants' wounds by beating them at AT&T Park two weeks ago.

San Francisco hopes the next elite pitcher to develop from its ranks is right-hander Kyle Crick, ranked No. 47 on the Top 100 Prospects list. He is the only Giant who made the Top 100 and has starred at Class A San Jose this season with a 1.04 ERA and 13 strikeouts per nine innings in eight starts.

Graduated

Conor Gillaspie is the lone player from the preseason Top 20 to graduate from the list, but he is no longer in the organization.

Gillaspie played in parts of three seasons at the big league level, but San Francisco traded him to the White Sox during Spring Training for pitcher Jeff Soptic. Gillaspie has played in 82 games for last-place Chicago with a .249 average, .310 on-base percentage, eight home runs and 24 RBIs.

Dropped off

Ehire Adrianza, Ricky Oropesa and Chris Heston are the three prospects omitted from the Giants' Top 20 after making the cut during the preseason.

Adrianza, a shortstop, was cut from big league camp midway through Spring Training and has not made much headway since. Most of his season has been spent with Double-A Richmond, where he has posted a lukewarm .240 average with two home runs and 23 RBIs in 73 games.

Oropesa clubbed 16 home runs and 98 RBIs with Class A San Jose in 2012, but he has struggled in 2013 with his time split between San Jose and Double-A Richmond. He is hitting just .207 with a .255 on-base percentage, six home runs and 23 RBIs in 66 games.

After earning a spot in the Giants' Top 20 with a 2.24 ERA in 148 2/3 innings for Double-A Richmond in 2012, Heston struggled this season and was released by the organization on Tuesday. He's not a hard thrower and appeared to be overmatched at Triple-A Fresno, where his ERA ballooned to 5.80 in 108 2/3 innings.

New faces

The Giants have four additions to the Top 20, three of which are courtesy of the 2013 First-Year Player Draft.

First-round pick Christian Arroyo -- whom San Francisco selected 25th overall in June -- moved up to the eighth spot on the Giants' Top 20 list.

Brian Ragira (No. 16) and Ryder Jones (17) also made the cut after being selected in the Draft a month ago. The Giants selected Ragira in the fourth round out of Stanford and Jones in the second round out of high school; Jones had committed to play ball at Stanford as well.

Josh Osich is the only addition to the Top 20 who was a member of the organization prior to June. The Giants nabbed Osich in the sixth round of the 2011 Draft. He pitched admirably with Class A San Jose last year (3.62 ERA) and in 2013 (2.45 ERA) before earning a promotion to Double-A Richmond, where he has struggled in a small sample size.

giants' top prospects

Arroyo jumped 13 spots, making him the largest riser on the list. But as for players who were in the organization when the Top 20 preseason list was made, right-handed pitcher Clayton Blackburn earns top honors, moving from 13th to fifth.

Blackburn impressed at Class A Augusta in 2012 with a 2.54 ERA in 22 starts. He has followed it up this season with a 5-4 record and a 4.26 ERA at Class A San Jose. The 2011 16th-round pick has struck out 10.1 batters per nine innings this year.

Outfielder Gary Brown has experienced the biggest drop on the Top 20 list, falling from second to ninth overall. The Giants' 2010 first-round pick started slowly in 2013 but has improved his power numbers since. Overall, he is hitting .244 with a .305 on-base percentage, 12 home runs and 46 RBIs in 98 games this season with Triple-A Fresno.

Top 100 representation

San Francisco has moved up 38 points in the MLB.com "prospect points" rankings but remains 26th overall in Major League Baseball. As previously noted, Crick is the only Top 100 player in the Giants' Minor League system. Brown also made the list in Spring Training -- coming in at No. 100 -- but has since fallen from the rankings.

The Giants are one of four clubs with just one Top 100 player. The Braves are the only organization with zero. By comparison, National League West foes San Diego, Arizona and Los Angeles have four Top 100 players, and Colorado has three.

Andrew Owens is an associate reporter for MLB.com. Follow him on Twitter @OwensAndrew. This story was not subject to the approval of Major League Baseball or its clubs.